Figure 1

Melatonin responsiveness and MT1 receptor expression of a panel of human breast cancer cells. (a) The relative invasive potential of MCF-7, MCF-7/AZ, MCF-7/6, MCF-7/vec, MCF-7/Her2.1, and MCF-7/CXCR4 breast cancer cells. Data are presented as fold of control (MCF-7, set as 1). *P < 0.05 versus MCF-7 cells. (b) Western blot analysis of MT1 protein expression in MCF-7, MCF-7/CXCR4, MCF-7/Her2.1, and MCF-7/6 cells. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) protein levels are shown as loading control. (c) Effect of melatonin on cell proliferation in MCF-7, MCF-7/AZ, MCF-7/6, MCF-7/Her2.1, and MDA-MB-231 cells. Cells were serum-starved for 24 hours and treated with melatonin (Mlt, 10^-9 M) or diluent (Control, 0.00001% ethanol). Cell numbers were determined on day 6 by hemacytometer cell count. Data are presented as percentage of mean cell count in vehicle-treated cells (100%). One-way analysis of variance followed by Student Newman-Keuls post hoc test analyses was used to determine statistically significant differences in the cell number between melatonin- and vehicle-treated groups. *P < 0.05 versus vehicle-treated cells (n = 3).